Typical tea processes for making tea concentrates use high extraction temperatures to ensure high yields and flavor component recovery. This is particularly true for black tea and also applies to green tea and oolong teas. The main disadvantages when this technique is used for green and oolong teas are that the resulting extracts are very bitter and astringent and are thus difficult to use, especially in non-tea beverage matrices, without eliciting consumer responses such as "astringent" and "harsh" when describing the resulting beverages.
An example of this problem is the process for making green tea solids as described in U.S. Pat. No. 4,935,256 awarded to Tsai et al., where the resulting tea solids had an astringent taste when incorporated in beverages. This had to be masked with various materials in order to make the beverages acceptable.
On the other hand many beneficial effects of green tea solids and of the flavanols are suggested by the literature. For example the caffeine in tea extracts does not appear to be as physiologically available as the caffeine in coffee. In fact green tea is believed to have a relaxing benefit owing to the flavanols ( i.e., catechins and epicatechins) present in green tea. The use of these materials with caffeine in a stable form in beverages is described in U.S. Pat. No. 4,946,701 awarded to Kuznicki et al.
In view of the above mentioned processing difficulties, typical tea processes to obtain these flavanols often includes extracting primarily the high quality teas or extraction of the leaf and the immediately adjoining stems and leaves from choice grade teas. Lower grade teas, made from less suitable leaves and plants are generally considered inferior due to the harsh and astringent taste character.
The harshness and astringency of green tea is known to be largely dependent on the flavanols and caffeine. The harsh taste is believed to be mitigated by the free amino acids, especially that of theanine. Theanine or 5-(N-ethyl)-glutamine is unique to Camellia species, from which genus, green and black teas are made.
An object of this invention is to remove fractions of the flavor attributed to negative taste and to provide a method of improving or mellowing extracts of all but especially low grade teas.
A particular object of the subject invention is to provide tea extracts containing tea solids, including caffeine, amino acids, especially higher levels of theanine, flavanols and very little oxidized or polymerized flavanols or polyphenols. This product is less astringent and less harsh in taste and provides all of the benefits of the green tea solid/caffeine mixtures.
A further object of the subject invention is to provide processes for obtaining such tea extracts.
Another object of this invention is to provide a beverage which provides the beneficial effects of this extract and which is stable in liquid form.
Still a further object of this invention is to provide a beverage which contains caffeine and which provides the alertness benefit of caffeine along with the beneficial effects of the flavanols and other green tea solids.
These and other objects will become apparent from the description herein.
All percentages are by weight unless otherwise indicated.